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At 115200 we expect ~100us between interrupts, or around 5% CPU overhead. 4us latency is probably acceptable for servo signal jitter too if we decide to consider using the Arduino Servo library. git-svn-id: https://arducopter.googlecode.com/svn/trunk@513 f9c3cf11-9bcb-44bc-f272-b75c42450872master
DrZiplok@gmail.com
15 years ago
3 changed files with 368 additions and 388 deletions
@ -1,358 +1,324 @@
@@ -1,358 +1,324 @@
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// -*- Mode: C++; c-basic-offset: 8; indent-tabs-mode: nil -*-
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//
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// Interrupt-driven serial transmit/receive library.
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//
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// Copyright (c) 2010 Michael Smith. All rights reserved.
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//
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// Receive and baudrate calculations derived from the Arduino
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// HardwareSerial driver:
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//
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// Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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//
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// Transmit algorithm inspired by work:
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//
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// Code Jose Julio and Jordi Munoz. DIYDrones.com
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
|
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// License as published by the Free Software Foundation; either
|
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// version 2.1 of the License, or (at your option) any later version.
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//
|
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
|
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// You should have received a copy of the GNU Lesser General Public
|
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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//
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//#include "../AP_Common/AP_Common.h"
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#include "FastSerial.h" |
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#include "WProgram.h" |
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#if defined(__AVR_ATmega1280__) |
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# define FS_MAX_PORTS 4 |
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#else |
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# define FS_MAX_PORTS 1 |
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#endif |
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FastSerial *__FastSerial__ports[FS_MAX_PORTS]; |
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// Default buffer sizes
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#define RX_BUFFER_SIZE 128 |
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#define TX_BUFFER_SIZE 64 |
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#define BUFFER_MAX 512 |
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// Interrupt handlers //////////////////////////////////////////////////////////
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#if 0 |
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#define HANDLERS(_PORT, _RXVECTOR, _TXVECTOR, _UDR) \ |
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SIGNAL(_RXVECTOR) \
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{ \
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unsigned char c = _UDR; \
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ports[_PORT]->receive(c); \
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} \
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\
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SIGNAL(_TXVECTOR) \
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{ \
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ports[_PORT]->transmit(); \
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} \
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struct hack |
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#if defined(__AVR_ATmega8__) |
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HANDLERS(0, SIG_UART_RECV, SIG_UART_DATA, UDR); |
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#else |
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HANDLERS(0, SIG_USART0_RECV, SIG_USART0_DATA, UDR0); |
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#if defined(__AVR_ATmega1280__) |
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HANDLERS(1, SIG_USART1_RECV, SIG_USART1_DATA, UDR1); |
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HANDLERS(2, SIG_USART2_RECV, SIG_USART2_DATA, UDR2); |
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HANDLERS(3, SIG_USART3_RECV, SIG_USART3_DATA, UDR3); |
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#endif |
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#endif |
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#endif |
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// Constructor /////////////////////////////////////////////////////////////////
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FastSerial::FastSerial(const uint8_t portNumber, |
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volatile uint8_t *ubrrh, |
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volatile uint8_t *ubrrl, |
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volatile uint8_t *ucsra, |
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volatile uint8_t *ucsrb, |
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volatile uint8_t *udr, |
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const uint8_t u2x, |
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const uint8_t portEnableBits, |
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const uint8_t portTxBits) |
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{ |
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_ubrrh = ubrrh; |
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_ubrrl = ubrrl; |
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_ucsra = ucsra; |
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_ucsrb = ucsrb; |
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_udr = udr; |
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_u2x = u2x; |
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_portEnableBits = portEnableBits; |
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_portTxBits = portTxBits; |
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// init buffers
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_txBuffer.head = _txBuffer.tail = 0; |
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_rxBuffer.head = _rxBuffer.tail = 0; |
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// claim the port
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__FastSerial__ports[portNumber] = this; |
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// init stdio
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fdev_setup_stream(&_fd, &FastSerial::_putchar, NULL, _FDEV_SETUP_WRITE); |
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fdev_set_udata(&_fd, this); |
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if (0 == portNumber) |
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stdout = &_fd; // serial port 0 is always the default console
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} |
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// Public Methods //////////////////////////////////////////////////////////////
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void FastSerial::begin(long baud) |
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{ |
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begin(baud, RX_BUFFER_SIZE, TX_BUFFER_SIZE); |
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} |
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void FastSerial::begin(long baud, unsigned int rxSpace, unsigned int txSpace) |
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{ |
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uint16_t baud_setting; |
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bool use_u2x; |
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// if we are currently open, close and restart
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if (_open) |
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end(); |
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// allocate buffers
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if (!_allocBuffer(&_rxBuffer, rxSpace ? : RX_BUFFER_SIZE) || |
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!_allocBuffer(&_txBuffer, txSpace ? : TX_BUFFER_SIZE)) { |
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end(); |
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return; // couldn't allocate buffers - fatal
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} |
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_open = true; |
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// U2X mode is needed for baud rates higher than (CPU Hz / 16)
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if (baud > F_CPU / 16) { |
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use_u2x = true; |
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} else { |
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// figure out if U2X mode would allow for a better connection
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// calculate the percent difference between the baud-rate specified and
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// the real baud rate for both U2X and non-U2X mode (0-255 error percent)
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uint8_t nonu2x_baud_error = abs((int)(255-((F_CPU/(16*(((F_CPU/8/baud-1)/2)+1))*255)/baud))); |
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uint8_t u2x_baud_error = abs((int)(255-((F_CPU/(8*(((F_CPU/4/baud-1)/2)+1))*255)/baud))); |
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// prefer non-U2X mode because it handles clock skew better
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use_u2x = (nonu2x_baud_error > u2x_baud_error); |
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} |
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if (use_u2x) { |
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*_ucsra = _BV(_u2x); |
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baud_setting = (F_CPU / 4 / baud - 1) / 2; |
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} else { |
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*_ucsra = 0; |
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baud_setting = (F_CPU / 8 / baud - 1) / 2; |
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} |
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// assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)
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*_ubrrh = baud_setting >> 8; |
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*_ubrrl = baud_setting; |
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*_ucsrb |= _portEnableBits; |
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} |
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void FastSerial::end() |
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{ |
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*_ucsrb &= ~(_portEnableBits | _portTxBits); |
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_freeBuffer(&_rxBuffer); |
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_freeBuffer(&_txBuffer); |
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_open = false; |
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} |
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int |
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FastSerial::available(void) |
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{ |
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if (!_open) |
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return(-1); |
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return((_rxBuffer.head - _rxBuffer.tail) & _rxBuffer.mask); |
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} |
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int |
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FastSerial::read(void) |
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{ |
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uint8_t c; |
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// if the head and tail are equal, the buffer is empty
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if (!_open || (_rxBuffer.head == _rxBuffer.tail)) |
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return(-1); |
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// pull character from tail
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c = _rxBuffer.bytes[_rxBuffer.tail]; |
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_rxBuffer.tail = (_rxBuffer.tail + 1) & _rxBuffer.mask; |
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return(c); |
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} |
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void |
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FastSerial::flush(void) |
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{ |
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// don't reverse this or there may be problems if the RX interrupt
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// occurs after reading the value of _rxBuffer.head but before writing
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// the value to _rxBuffer.tail; the previous value of head
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// may be written to tail, making it appear as if the buffer
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// don't reverse this or there may be problems if the RX interrupt
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// occurs after reading the value of head but before writing
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// the value to tail; the previous value of rx_buffer_head
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// may be written to tail, making it appear as if the buffer
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// were full, not empty.
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_rxBuffer.head = _rxBuffer.tail; |
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// don't reverse this or there may be problems if the TX interrupt
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// occurs after reading the value of _txBuffer.tail but before writing
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// the value to _txBuffer.head.
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_txBuffer.tail = _rxBuffer.head; |
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} |
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void |
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FastSerial::write(uint8_t c) |
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{ |
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int16_t i; |
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if (!_open) // drop bytes if not open
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return; |
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// wait for room in the tx buffer
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i = (_txBuffer.head + 1) & _txBuffer.mask; |
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while (i == _txBuffer.tail) |
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; |
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// add byte to the buffer
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_txBuffer.bytes[_txBuffer.head] = c; |
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_txBuffer.head = i; |
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// enable the data-ready interrupt, as it may be off if the buffer is empty
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*_ucsrb |= _portTxBits; |
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} |
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// STDIO emulation /////////////////////////////////////////////////////////////
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int |
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FastSerial::_putchar(char c, FILE *stream) |
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{ |
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FastSerial *fs; |
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fs = (FastSerial *)fdev_get_udata(stream); |
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fs->write(c); |
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return(0); |
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} |
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int |
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FastSerial::_getchar(FILE *stream) |
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{ |
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FastSerial *fs; |
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fs = (FastSerial *)fdev_get_udata(stream); |
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// We return -1 if there is nothing to read, which the library interprets
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// as an error, which our clients will need to deal with.
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return(fs->read()); |
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} |
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int |
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FastSerial::printf(const char *fmt, ...) |
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{ |
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va_list ap; |
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int i; |
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va_start(ap, fmt); |
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i = vfprintf(&_fd, fmt, ap); |
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va_end(ap); |
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return(i); |
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} |
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int |
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FastSerial::printf_P(const char *fmt, ...) |
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{ |
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va_list ap; |
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int i; |
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va_start(ap, fmt); |
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i = vfprintf_P(stdout, fmt, ap); |
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va_end(ap); |
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return(i); |
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} |
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// Interrupt methods ///////////////////////////////////////////////////////////
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void |
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FastSerial::receive(uint8_t c) |
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{ |
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uint8_t i; |
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// if we should be storing the received character into the location
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// just before the tail (meaning that the head would advance to the
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// current location of the tail), we're about to overflow the buffer
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// and so we don't write the character or advance the head.
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i = (_rxBuffer.head + 1) & _rxBuffer.mask; |
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if (i != _rxBuffer.tail) { |
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_rxBuffer.bytes[_rxBuffer.head] = c; |
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_rxBuffer.head = i; |
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} |
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} |
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void |
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FastSerial::transmit(void) |
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{ |
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// if the buffer is not empty, send the next byte
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if (_txBuffer.head != _txBuffer.tail) { |
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*_udr = _txBuffer.bytes[_txBuffer.tail]; |
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_txBuffer.tail = (_txBuffer.tail + 1) & _txBuffer.mask; |
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} |
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// if the buffer is (now) empty, disable the interrupt
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if (_txBuffer.head == _txBuffer.tail) |
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*_ucsrb &= ~_portTxBits; |
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} |
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// Buffer management ///////////////////////////////////////////////////////////
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bool |
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FastSerial::_allocBuffer(Buffer *buffer, unsigned int size) |
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{ |
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uint8_t shift; |
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// init buffer state
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buffer->head = buffer->tail = 0; |
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// cap the buffer size
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if (size > BUFFER_MAX) |
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size = BUFFER_MAX; |
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// compute the power of 2 greater or equal to the requested buffer size
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// and then a mask to simplify wrapping operations
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shift = 16 - __builtin_clz(size - 1); |
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buffer->mask = (1 << shift) - 1; |
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// allocate memory for the buffer - if this fails, we fail
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buffer->bytes = (uint8_t *)malloc(buffer->mask + 1); |
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return(buffer->bytes != NULL); |
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} |
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void |
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FastSerial::_freeBuffer(Buffer *buffer) |
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{ |
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buffer->head = buffer->tail = 0; |
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buffer->mask = 0; |
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if (NULL != buffer->bytes) { |
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free(buffer->bytes); |
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buffer->bytes = NULL; |
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} |
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} |
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// -*- Mode: C++; c-basic-offset: 8; indent-tabs-mode: nil -*-
|
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//
|
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// Interrupt-driven serial transmit/receive library.
|
||||
//
|
||||
// Copyright (c) 2010 Michael Smith. All rights reserved.
|
||||
//
|
||||
// Receive and baudrate calculations derived from the Arduino
|
||||
// HardwareSerial driver:
|
||||
//
|
||||
// Copyright (c) 2006 Nicholas Zambetti. All right reserved.
|
||||
//
|
||||
// Transmit algorithm inspired by work:
|
||||
//
|
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// Code Jose Julio and Jordi Munoz. DIYDrones.com
|
||||
//
|
||||
// This library is free software; you can redistribute it and/or
|
||||
// modify it under the terms of the GNU Lesser General Public
|
||||
// License as published by the Free Software Foundation; either
|
||||
// version 2.1 of the License, or (at your option) any later version.
|
||||
//
|
||||
// This library is distributed in the hope that it will be useful,
|
||||
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
// Lesser General Public License for more details.
|
||||
//
|
||||
// You should have received a copy of the GNU Lesser General Public
|
||||
// License along with this library; if not, write to the Free Software
|
||||
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
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//
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//#include "../AP_Common/AP_Common.h"
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#include "FastSerial.h" |
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#include "WProgram.h" |
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#if defined(__AVR_ATmega1280__) |
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# define FS_MAX_PORTS 4 |
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#else |
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# define FS_MAX_PORTS 1 |
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#endif |
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FastSerial::Buffer __FastSerial__rxBuffer[FS_MAX_PORTS]; |
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FastSerial::Buffer __FastSerial__txBuffer[FS_MAX_PORTS]; |
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// Default buffer sizes
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#define RX_BUFFER_SIZE 128 |
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#define TX_BUFFER_SIZE 64 |
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#define BUFFER_MAX 512 |
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// Interrupt handlers //////////////////////////////////////////////////////////
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#if 0 |
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#define HANDLERS(_PORT, _RXVECTOR, _TXVECTOR, _UDR) \ |
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SIGNAL(_RXVECTOR) \
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{ \
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unsigned char c = _UDR; \
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ports[_PORT]->receive(c); \
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} \
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\
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SIGNAL(_TXVECTOR) \
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{ \
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ports[_PORT]->transmit(); \
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} \
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struct hack |
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#if defined(__AVR_ATmega8__) |
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HANDLERS(0, SIG_UART_RECV, SIG_UART_DATA, UDR); |
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#else |
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HANDLERS(0, SIG_USART0_RECV, SIG_USART0_DATA, UDR0); |
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#if defined(__AVR_ATmega1280__) |
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HANDLERS(1, SIG_USART1_RECV, SIG_USART1_DATA, UDR1); |
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HANDLERS(2, SIG_USART2_RECV, SIG_USART2_DATA, UDR2); |
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HANDLERS(3, SIG_USART3_RECV, SIG_USART3_DATA, UDR3); |
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#endif |
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#endif |
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#endif |
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// Constructor /////////////////////////////////////////////////////////////////
|
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|
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FastSerial::FastSerial(const uint8_t portNumber, |
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volatile uint8_t *ubrrh, |
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volatile uint8_t *ubrrl, |
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volatile uint8_t *ucsra, |
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volatile uint8_t *ucsrb, |
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volatile uint8_t *udr, |
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const uint8_t u2x, |
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const uint8_t portEnableBits, |
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const uint8_t portTxBits) |
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{ |
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_ubrrh = ubrrh; |
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_ubrrl = ubrrl; |
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_ucsra = ucsra; |
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_ucsrb = ucsrb; |
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_udr = udr; |
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_u2x = u2x; |
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_portEnableBits = portEnableBits; |
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_portTxBits = portTxBits; |
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// init buffers
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_rxBuffer = &__FastSerial__rxBuffer[portNumber]; |
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_txBuffer->head = _txBuffer->tail = 0; |
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_txBuffer = &__FastSerial__txBuffer[portNumber]; |
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_rxBuffer->head = _rxBuffer->tail = 0; |
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|
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// init stdio
|
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fdev_setup_stream(&_fd, &FastSerial::_putchar, NULL, _FDEV_SETUP_WRITE); |
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fdev_set_udata(&_fd, this); |
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if (0 == portNumber) |
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stdout = &_fd; // serial port 0 is always the default console
|
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} |
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|
||||
// Public Methods //////////////////////////////////////////////////////////////
|
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|
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void FastSerial::begin(long baud) |
||||
{ |
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begin(baud, RX_BUFFER_SIZE, TX_BUFFER_SIZE); |
||||
} |
||||
|
||||
void FastSerial::begin(long baud, unsigned int rxSpace, unsigned int txSpace) |
||||
{ |
||||
uint16_t baud_setting; |
||||
bool use_u2x; |
||||
|
||||
// if we are currently open, close and restart
|
||||
if (_open) |
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end(); |
||||
|
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// allocate buffers
|
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if (!_allocBuffer(_rxBuffer, rxSpace ? : RX_BUFFER_SIZE) || |
||||
!_allocBuffer(_txBuffer, txSpace ? : TX_BUFFER_SIZE)) { |
||||
end(); |
||||
return; // couldn't allocate buffers - fatal
|
||||
} |
||||
_open = true; |
||||
|
||||
// U2X mode is needed for baud rates higher than (CPU Hz / 16)
|
||||
if (baud > F_CPU / 16) { |
||||
use_u2x = true; |
||||
} else { |
||||
// figure out if U2X mode would allow for a better connection
|
||||
|
||||
// calculate the percent difference between the baud-rate specified and
|
||||
// the real baud rate for both U2X and non-U2X mode (0-255 error percent)
|
||||
uint8_t nonu2x_baud_error = abs((int)(255-((F_CPU/(16*(((F_CPU/8/baud-1)/2)+1))*255)/baud))); |
||||
uint8_t u2x_baud_error = abs((int)(255-((F_CPU/(8*(((F_CPU/4/baud-1)/2)+1))*255)/baud))); |
||||
|
||||
// prefer non-U2X mode because it handles clock skew better
|
||||
use_u2x = (nonu2x_baud_error > u2x_baud_error); |
||||
} |
||||
|
||||
if (use_u2x) { |
||||
*_ucsra = _BV(_u2x); |
||||
baud_setting = (F_CPU / 4 / baud - 1) / 2; |
||||
} else { |
||||
*_ucsra = 0; |
||||
baud_setting = (F_CPU / 8 / baud - 1) / 2; |
||||
} |
||||
|
||||
// assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)
|
||||
*_ubrrh = baud_setting >> 8; |
||||
*_ubrrl = baud_setting; |
||||
|
||||
*_ucsrb |= _portEnableBits; |
||||
} |
||||
|
||||
void FastSerial::end() |
||||
{ |
||||
*_ucsrb &= ~(_portEnableBits | _portTxBits); |
||||
|
||||
_freeBuffer(_rxBuffer); |
||||
_freeBuffer(_txBuffer); |
||||
_open = false; |
||||
} |
||||
|
||||
int |
||||
FastSerial::available(void) |
||||
{ |
||||
if (!_open) |
||||
return(-1); |
||||
return((_rxBuffer->head - _rxBuffer->tail) & _rxBuffer->mask); |
||||
} |
||||
|
||||
int |
||||
FastSerial::read(void) |
||||
{ |
||||
uint8_t c; |
||||
|
||||
// if the head and tail are equal, the buffer is empty
|
||||
if (!_open || (_rxBuffer->head == _rxBuffer->tail)) |
||||
return(-1); |
||||
|
||||
// pull character from tail
|
||||
c = _rxBuffer->bytes[_rxBuffer->tail]; |
||||
_rxBuffer->tail = (_rxBuffer->tail + 1) & _rxBuffer->mask; |
||||
|
||||
return(c); |
||||
} |
||||
|
||||
void |
||||
FastSerial::flush(void) |
||||
{ |
||||
// don't reverse this or there may be problems if the RX interrupt
|
||||
// occurs after reading the value of _rxBuffer->head but before writing
|
||||
// the value to _rxBuffer->tail; the previous value of head
|
||||
// may be written to tail, making it appear as if the buffer
|
||||
// don't reverse this or there may be problems if the RX interrupt
|
||||
// occurs after reading the value of head but before writing
|
||||
// the value to tail; the previous value of rx_buffer_head
|
||||
// may be written to tail, making it appear as if the buffer
|
||||
// were full, not empty.
|
||||
_rxBuffer->head = _rxBuffer->tail; |
||||
|
||||
// don't reverse this or there may be problems if the TX interrupt
|
||||
// occurs after reading the value of _txBuffer->tail but before writing
|
||||
// the value to _txBuffer->head.
|
||||
_txBuffer->tail = _rxBuffer->head; |
||||
} |
||||
|
||||
void |
||||
FastSerial::write(uint8_t c) |
||||
{ |
||||
int16_t i; |
||||
|
||||
if (!_open) // drop bytes if not open
|
||||
return; |
||||
|
||||
// wait for room in the tx buffer
|
||||
i = (_txBuffer->head + 1) & _txBuffer->mask; |
||||
while (i == _txBuffer->tail) |
||||
; |
||||
|
||||
// add byte to the buffer
|
||||
_txBuffer->bytes[_txBuffer->head] = c; |
||||
_txBuffer->head = i; |
||||
|
||||
// enable the data-ready interrupt, as it may be off if the buffer is empty
|
||||
*_ucsrb |= _portTxBits; |
||||
} |
||||
|
||||
// STDIO emulation /////////////////////////////////////////////////////////////
|
||||
|
||||
int |
||||
FastSerial::_putchar(char c, FILE *stream) |
||||
{ |
||||
FastSerial *fs; |
||||
|
||||
fs = (FastSerial *)fdev_get_udata(stream); |
||||
fs->write(c); |
||||
return(0); |
||||
} |
||||
|
||||
int |
||||
FastSerial::_getchar(FILE *stream) |
||||
{ |
||||
FastSerial *fs; |
||||
|
||||
fs = (FastSerial *)fdev_get_udata(stream); |
||||
|
||||
// We return -1 if there is nothing to read, which the library interprets
|
||||
// as an error, which our clients will need to deal with.
|
||||
return(fs->read()); |
||||
} |
||||
|
||||
int |
||||
FastSerial::printf(const char *fmt, ...) |
||||
{ |
||||
va_list ap; |
||||
int i; |
||||
|
||||
va_start(ap, fmt); |
||||
i = vfprintf(&_fd, fmt, ap); |
||||
va_end(ap); |
||||
|
||||
return(i); |
||||
} |
||||
|
||||
int |
||||
FastSerial::printf_P(const char *fmt, ...) |
||||
{ |
||||
va_list ap; |
||||
int i; |
||||
|
||||
va_start(ap, fmt); |
||||
i = vfprintf_P(stdout, fmt, ap); |
||||
va_end(ap); |
||||
|
||||
return(i); |
||||
} |
||||
|
||||
// Buffer management ///////////////////////////////////////////////////////////
|
||||
|
||||
bool |
||||
FastSerial::_allocBuffer(Buffer *buffer, unsigned int size) |
||||
{ |
||||
uint8_t shift; |
||||
|
||||
// init buffer state
|
||||
buffer->head = buffer->tail = 0; |
||||
|
||||
// Compute the power of 2 greater or equal to the requested buffer size
|
||||
// and then a mask to simplify wrapping operations. Using __builtin_clz
|
||||
// would seem to make sense, but it uses a 256(!) byte table.
|
||||
// Note that we ignore requests for more than BUFFER_MAX space.
|
||||
for (shift = 1; (1U << shift) < min(BUFFER_MAX, size); shift++) |
||||
; |
||||
buffer->mask = (1 << shift) - 1; |
||||
|
||||
// allocate memory for the buffer - if this fails, we fail
|
||||
buffer->bytes = (uint8_t *)malloc(buffer->mask + 1); |
||||
|
||||
return(buffer->bytes != NULL); |
||||
} |
||||
|
||||
void |
||||
FastSerial::_freeBuffer(Buffer *buffer) |
||||
{ |
||||
buffer->head = buffer->tail = 0; |
||||
buffer->mask = 0; |
||||
if (NULL != buffer->bytes) { |
||||
free(buffer->bytes); |
||||
buffer->bytes = NULL; |
||||
} |
||||
} |
||||
|
||||
|
Loading…
Reference in new issue